Adhesive fluorine-containing polymer and laminate employing it

ABSTRACT

An adhesive fluorine-containing polymer comprising a fluorine-containing polymer having hydrogen atoms bonded to carbon atoms of its main chain and a grafting compound having a linking group capable of grafting to the fluorine-containing polymer and a functional group capable of providing an adhesive property, grafted to the fluorine-containing polymer.

This application is a Continuation of application Ser. No. 08/330,869filed on Oct. 28, 1994, now abandoned.

The present invention relates to an adhesive fluorine-containing polymerwhich can be firmly bonded to substrates made of various organicmaterials or inorganic materials, and a laminate prepared by using it.

A fluorine-containing polymer is excellent in the chemical resistance,weather resistance and surface properties and thus is widely used inmany fields. One of applications of such a fluorine-containing polymeris an application as a laminate. For example, an application as asurface coating material is known in which e.g. a film of afluorine-containing polymer is laminated on the surface of a substratemade of an inorganic material or an organic material such as a syntheticresin, to cover the substrate. However, a fluorine-containing polymer isa material which inherently has poor adhesive properties, and in manycases, no adequate adhesive strength can be obtained if e.g. a film of afluorine-containing polymer is laminated directly on a substrate. Evenwhen an adhesive strength can be obtained to some extent, such anadhesive strength is likely to vary depending upon the type of thematerial of the substrate, whereby the reliability of the adhesion hasbeen inadequate in many cases.

An adhesive to bond a fluorine-containing polymer is known. However,such an adhesive is poor in the chemical resistance or water resistanceas compared with the fluorine-containing polymer and has frequentlycaused a problem for a laminate employing a fluorine-containing polymer.Further, in order to use such an adhesive, it has been required to use aprimer, or to apply surface treatment to the fluorine-containingpolymer, in many cases.

Under these circumstances, it is an object of the present invention toprovide a fluorine-containing polymer having excellent adhesiveproperties.

It is another object of the present invention to provide a laminateemploying such an adhesive fluorine-containing polymer, such as alaminate having such an adhesive fluorine-containing polymer laminatedon a substrate made of various organic materials or inorganic materials,or a laminate in which such an adhesive fluorine-containing polymer isused as an adhesive to laminate another fluorine-containing polymer on asubstrate made of various materials.

The present invention provides an adhesive fluorine-containing polymercomprising a fluorine-containing polymer having hydrogen atoms bonded tocarbon atoms of its main chain and a grafting compound having a linkinggroup capable of grafting to the fluorine-containing polymer and afunctional group capable of providing an adhesive property, grafted tothe fluorine-containing polymer.

The present invention also provides a method for producing an adhesivefluorine-containing polymer, which comprises melt-mixing afluorine-containing polymer having hydrogen atoms bonded to carbon atomsof its main chain, a grafting compound having a linking group capable ofgrafting to the fluorine-containing polymer and a functional groupcapable of providing an adhesive property, and a radical-forming agent,at a radical-forming temperature, to graft the grafting compound to thefluorine-containing polymer.

Further, the present invention provides a method for forming a graftedfluorine-containing polymer, which comprises melt-mixing afluorine-containing polymer having hydrogen atoms bonded to carbon atomsof its main chain, a grafting compound having a linking group capable ofgrafting to the fluorine-containing polymer and a functional groupcapable of providing an adhesive property, and a radical-forming agent,in a molding machine at a radical-forming temperature, to graft thegrafting compound to the fluorine-containing polymer and at the sametime, molding the grafted fluorine-containing polymer.

The present invention further provides a laminate comprising a layer ofthe above-mentioned adhesive fluorine-containing polymer and a layer ofa resin made of another polymer laminated to the adhesivefluorine-containing polymer.

Still further, the present invention provides a method for producing alaminate having a grafted fluorine-containing polymer layer, whichcomprises melt-mixing a fluorine-containing polymer having hydrogenatoms bonded to carbon atoms of its main chain, a grafting compoundhaving a linking group capable of grafting to the fluorine-containingpolymer and a functional group capable of providing an adhesiveproperty, and a radical-forming agent, in a co-extrusion molding machineat a radical-forming temperature, to graft the grafting compound to thefluorine-containing polymer and at the same time, co-extrusion moldingthe grafted fluorine-containing polymer together with another materialto produce a laminate.

Now, the present invention will be described in detail with reference tothe preferred embodiments.

The fluorine-containing polymer before grafting, to be used in thepresent invention, is a fluorine-containing polymer of the type whichhas fluorine atoms on carbon atoms of its main chain. Further, it isrequired to have hydrogen atoms bonded to carbon atoms of its mainchain. Such a fluorine-containing polymer has a characteristic suchthat, as compared with fluorine atoms, the hydrogen atoms bonded to themain chain are relatively unstable and readily removed from the carbonatoms by the action of radicals. To the radicals of the carbon atomsfrom which the hydrogen atoms have been removed, the linking group ofthe grafting compound will bond, whereby grafting takes place. In thepresent invention, the grafting compound thus grafted, has a functionalgroup capable of providing an adhesive property, whereby an adhesiveproperty is imparted to the fluorine-containing polymer.

It is per se known to graft a compound having a linking group capable ofgrafting to a fluorine-containing polymer. For example, it is known tograft a compound having a crosslinkable group, followed by crosslinking,to obtain a crosslinked fluorine-containing polymer. Japanese UnexaminedPatent Publication No. 115234/1990 discloses that vinyl trimethoxysilaneis grafted to polyvinylidene fluoride under the action of a peroxide,followed by crosslinking with water to obtain a crosslinkedpolyvinylidene fluoride. However, it is not known that the graftedpolyvinylidene fluoride before crosslinking has an adhesive property andis useful for bonding to other materials.

As the fluorine-containing polymer before grafting to be used in thepresent invention, a homopolymer or a copolymer of a fluoroolefin ispreferred. However, in a case of a fluoroolefin having no hydrogen atomon either one of the two carbon atoms of the polymerizable unsaturatedgroup, such as tetrafluoroethylene or chlorotrifluoroethylene, it isnecessary to copolymerize it with a monomer having at least one hydrogenatom on either one of the two carbon atoms of the polymerizableunsaturated group.

As the fluoroolefin having hydrogen atoms on the polymerizableunsaturated group, vinylidene fluoride or vinyl fluoride may, forexample, be mentioned. A homopolymer of such a fluoroolefin can be usedas the fluorine-containing polymer before grafting to be used in thepresent invention. Further, a copolymer of such a monomer with anothermonomer may also be employed. As such another monomer, variousfluorine-containing monomers as well as monomers containing no fluorineatom, may be employed.

As the monomer to be copolymerized with a fluoroolefin having nohydrogen atom on either one of the two carbon atoms of the polymerizableunsaturated group, an olefin (namely, a hydrocarbon type olefin) ispreferred. Particularly preferred is an α-olefin such as ethylene,propylene or butene. However, the monomer is not limited to an α-olefin,and various monomers including fluoroolefins having hydrogen atoms onthe unsaturated groups, such as vinylidene fluoride and(perfluorobutyl)ethylene, vinyl ethers such as an alkylvinyl ether and a(fluoroalkyl)vinyl ether, and (meth)acrylates such as a (fluoroalkyl)methacrylate and a (fluoroalkyl) acrylate, may be used. Further,together with such a monomer, a monomer having no hydrogen atom on thepolymerizable unsaturated group, such as hexafluoroproplylene or aperfluoro(alkylvinyl ether) may be used as a third monomer.

In the present invention, preferred as the fluorine-containing polymerbefore grafting is a tetrafluoroethylene-ethylene copolymer, atetrafluoroethylene-propylene copolymer, a homopolymer or copolymer ofvinylidene fluoride, or a homopolymer or copolymer of vinyl fluoride.

As the tetrafluoroethylene-ethylene copolymer, the one in whichtetrafluoroethylene and ethylene are copolymerized in a molar ratio offrom 70/30 to 30/70, or the one wherein these monomers are copolymerizedwith one or more fluoroolefins or hydrocarbon olefins such as propylene,is, for example, preferred.

As the tetrafluoroethylene-propylene copolymer, the one whereintetrafluoroethylene and propylene are copolymerized in a molar ratio offrom 70/30 to 30/70, or the one wherein these monomers are copolymerizedwith one or more fluoroolefins or hydrocarbon olefins, is, for example,preferred.

As the vinylidene fluoride polymer, a homopolymer of vinylidene fluorideor a copolymer of vinylidene fluoride with various olefins orfluoroolefins, is, for example, preferred. Likewise, as the vinylfluoride polymer, a homopolymer of vinyl fluoride, or a copolymer ofvinyl fluoride with various olefins or fluoroolefins, is, for example,preferred.

In a case where the preferred fluorine-containing polymer is acopolymer, and the comonomer is a monomer containing no fluorine atom,it is preferred that the proportion of polymerized units of thefluorine-containing monomer in the fluorine-containing polymer is atleast 40 mol %, particularly at least 50 mol %, based on the totalpolymerized units.

If the proportion of the polymerized units of the fluorine-containingmonomer is lower than this range, the characteristic properties such asthe chemical resistance, weather resistance and surface properties, ofthe fluorine-containing polymer tend to deteriorate.

There is no particular limitation as to the molecular weight of thefluorine-containing polymer. It is useful within a wide range from a lowmolecular weight product which is liquid at room temperature to a highmolecular weight product which is rubber or a thermoplastic resin.Preferably, it is a polymer which is solid at room temperature, and itis useful by itself as a thermoplastic resin, elastomer or a rubber. Forthe production of such a polymer, any one of various conventionalmethods such as bulk polymerization, suspension polymerization, emulsionpolymerization and solution polymerization, may be employed.

In the present invention, the most preferred fluorine-containing polymeris the above-mentioned tetrafluoroethylene-ethylene copolymer. Thiscopolymer is referred to simply as ETFE. ETFE is thermoplastic and canbe readily formed into a film or sheet. Yet, it is excellent inmechanical properties such as strength and also has good chemicalresistance, weather resistance and surface properties. As describedhereinafter, even when a grafting compound is grafted thereto, theseproperties can be maintained, and improvement of the adhesive propertyby the grafting is remarkable. As such ETFE, a commercially availableproduct may also be used for the present invention.

By grafting a grafting compound to the fluorine-containing polymer, itis possible to obtain a fluorine-containing polymer having a largeadhesive strength even to a material to which the adhesion used to beinadequate or impossible. The linking group in the grafting compound isa group which makes grafting to the fluorine-containing polymerpossible. As such a linking group, an unsaturated or saturatedhydrocarbon group which is involved in addition or association ofradicals, or an amino group or a phenol group which is involved innucleophilic reaction, may, for example, be mentioned. Further, it maybe a group which readily forms radicals, such as a peroxy group or anazo group. Preferred linking groups include a group having acarbon-carbon unsaturated bond (particularly an organic group having anα,β-unsaturated double bond at its terminal), a peroxy group and anamino group.

The functional group capable of providing an adhesive property is agroup having a reactivity or polarity, which is capable of imparting anadhesive property to the grafted fluorine-containing polymer. Two ormore such functional groups may be present per molecule of the graftingcompound. Such two or more functional groups may be the same ordifferent from one another. Such a functional group may, for example, bea carboxyl group, a residual group having two carboxyl groups in onemolecule condensed by dehydration (hereinafter referred to as acarboxylic acid anhydride residue), an epoxy group, a hydroxyl group, anisocyanate group, an ester group, an acid amide group, an aldehydegroup, an amino group, a hydrolyzable group containing a silyl group ora cyano group.

Preferred as the functional group capable of imparting an adhesiveproperty are a carboxyl group, a carboxylic anhydride residue, an epoxygroup and a hydrolyzable group containing a silyl group. Particularlypreferred is a carboxylic anhydride residue.

Preferred as the grafting compound is a compound which, as mentionedabove, has a linking group selected from the group consisting of anorganic group having an α,β-unsaturated double bond at its terminal, aperoxy group and an amino group, and at least one functional groupselected from the group consisting of a carboxyl group, a carboxylicanhydride residue, an epoxy group and a hydrolyzable group containing asilyl group. Most preferred is an unsaturated polycarboxylic anhydride,and then, an unsaturated carboxylic acid, an epoxy group-containingunsaturated compound, a silyl-containing hydrolyzable group-containingunsaturated compound or an epoxy group-containing peroxy compound is,for example, preferred.

The unsaturated polycarboxylic anhydride may, for example, be maleicanhydride, itaconic anhydride, citraconic anhydride, crotonic anhydride,bicyclo 2.2.1!hept-2-ene-5,6-dicarboxylic anhydride, the unsaturatedcarboxylic anhydride may, for example, be acrylic acid, methacrylicacid, maleic acid, monomethyl maleate, fumaric acid, itaconic acid,citraconic acid, crotonic acid, or bicyclo2.2.1!hept-2-ene-5,6-dicarboxylic acid.

The epoxy group-containing unsaturated compound may, for example, beglycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether or allylglycidyl ester.

Preferred as the silyl-containing hydrolyzable group-containingunsaturated compound is a compound wherein one organic group containingan unsaturated group such as a vinyl group, an allyl group, amethacryloyloxyalkyl group or an acryloyloxyalkyl group and two or threehydrolyzable groups such as alkoxy groups or acyl groups are bonded to asilicon atom. When one unsaturated group-containing organic group and atleast one, preferably two or three hydrolyzable groups are bonded to asilicon atom, the remaining group is preferably a lower alkyl group suchas a methyl group. Specifically, such a silyl-containing hydrolyzablegroup-containing unsaturated compound may, for example, be vinyltrimethoxysilane, vinyl triethoxysilane, vinyl triacetoxysilane,γ-methacryloxypropyltrimethoxysilane or vinyltris(β-methoxyethoxy)silane.

The peroxy compound may, for example, a diacyl peroxide, a ketoneperoxide, a hydroperoxide or a peroxy carbonate, and it may further be acompound having the above described functional group. As the peroxycompound, a grafting compound of a polymer type which will be describedhereinafter, is particularly preferred.

The following unsaturated compounds may, for example, be mentioned asgrafting compounds other than those described above: an unsaturatedcompound having a hydroxyl group such as allyl alcohol, N-methylolacrylamide or N-methylol methacrylamide; an unsaturated carboxylate suchas methyl acrylate, methyl methacrylate, dimethyl maleate, diethylfumarate, dimethyl itaconate or diethyl citraconate; an unsaturatedamide such as acrylamide, N-methylacrylamide orN,N-dimethylmethacrylamide; an unsaturated amine such as allyl amine,methylaminoethyl methacrylate, t-butylaminoethyl methacrylate oraminostyrene; an unsaturated compound having a cyano group such as cyanoacrylate or cyano methacrylate; and an unsaturated aldehyde such asaclorein or croton aldehyde.

As described above, the grafting compound may be a compound having asaturated hydrocarbon group which is involved in addition or associationof radicals or a compound having an amino group or a phenol group whichis involved in a nucleophilic reaction, other than the above unsaturatedgroup-containing compound. The following compounds may, for example, bementioned as the grafting compound of this type: a compound having twoor more amino groups, or a compound having an amino group and anotherfunctional group, such as hexamethylenediamine, ethanolamine,diethanolamine, triethanolamine, γ-aminopropyltriethoxysilane,N-β(aminoethyl)γ-aminopropylmethyldimethoxysilane,N-β(aminoethyl)γ-aminopropylmethyldimethoxysilane, orγ-anilinopropyltrimethoxysilane.

The grafting compound may be a polymer having a linking group such as aperoxy group or an amino group and a functional group capable ofproviding an adhesive property. For example, a copolymer of apolymerizable unsaturated peroxide such ast-butylperoxymethacryloyloxyethyl carbonate with a polymerizableunsaturated compound having a carboxyl group, a carboxylic anhydrideresidue, an epoxy group or a hydrolyzable group containing a silylgroup, can be used as the grafting compound. Likewise, a copolymerobtained by copolymerizing a polymerizable unsaturated amine with theabove-mentioned polymerizable unsaturated compound having a functionalgroup, may also be used.

The amount of the grafting compound to be used for grafting is usuallyfrom 0.01 to 100 parts by weight, preferably from 0.1 to 20 parts byweight, per 100 parts by weight of the fluorine-containing polymer. Inthe case of a grafting compound of a polymer type, it may be used in alarger amount. However, the upper limit is preferably at a level ofabout 50 parts by weight. A preferred amount of the grafting compoundother than the polymer type, is from 0.5 to 10 parts by weight. If theamount of the grafting compound used, is too small, it will be difficultto obtain a fluorine-containing polymer having an adequate adhesiveproperty. On the other hand, if the amount is too much, the excellentproperties of the fluorine-containing polymer tend to be impaired.

As a method for grafting the grafting compound to thefluorine-containing polymer, a method is preferred wherein bothreactants are subjected to an association reaction in the presence of aradical-forming agent. However, when a radical-forming grafting compoundsuch as a compound having a peroxy group is employed, it is unnecessaryto use other radical-forming agent. The amount of the radical-formingagent is not particularly limited, but is usually from 0.1 to 10 partsby weight per part by weight of the grafting compound.

The grafting is believed to be accomplished by the following reactionmechanism. Firstly, a radical formed from the radical-forming agent willremove a hydrogen atom from the fluorine-containing polymer to form afluorine-containing polymer radical. On the other hand, a radical formedfrom the radical-forming agent will attach to the grafting compound orwill remove a hydrogen atom from the grafting compound to form aradical. Then, both radicals will associate to complete grafting.Otherwise grafting can be achieved also by direct addition of thefluorine-containing polymer radical to an unsaturated hydrocarbon groupof the grafting compound. Grafting is believed to occur also by variousother reaction mechanisms.

The grafting reaction is preferably conducted by melt-mixing thefluorine-containing polymer and the grafting compound, together with aradical-forming agent when such a radical-forming agent is required, ata radical-forming temperature. In some cases, a solvent may be used toform a fluorine-containing polymer solution, and the grafting reactionmay be conducted in this solution. It is most preferred to employ amethod wherein the grafting reaction is carried out while conducting themelt-mixing in an extrusion molding machine or an injection moldingmachine. The grafted fluorine-containing polymer may be formed into amolding material such as pellets. Further, the grafting may be conductedin a molding machine such as an extrusion molding machine, followed bymolding to obtain a molded product.

It is preferred that the radical-forming agent to be used for thegrafting reaction has a decomposition temperature within a range of from120° to 350° C. and its half-life period at the grafting reactiontemperature is about one minute. Specifically, benzoyl peroxide,dichlorobenzoyl peroxide, dicumyl peroxide,2,5-dimethyl-2,5-di(benzoylperoxy)hexyne-3,1,4-bis(tert-butylperoxyisopropyl)benzenelauroyl peroxide, t-butyl peracetate,2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3,2,5-dimethyl-2,5-di(t-butylperoxy)hexane,t-butyl perbenzoate or t-butyl perphenylacetate is, for example,preferred.

Likewise, as the above-mentioned polymerizable unsaturated peroxide, itis preferred that the decomposition temperature of the peroxy group inthe copolymer is within a range of from 120° to 350° C., and thehalf-life period at the grafting reaction temperature is about oneminute. As a specific polymerizable unsaturated peroxide, t-butylperoxymethacryloyloxyethyl carbonate, t-butylperoxyallyl carbonate,t-amylperoxyacryloyloxyethyl carbonate, t-hexylperoxyacryloyloxyethylcarbonate, 1,1,3,3-tetramethylbutylperoxyacryloyoxyethyl carbonate,t-butylperoxy methacrylate, cumylperoxyacryloyloxyethyl carbonate orp-isopropylcumylperoxyacryloyloxyethyl carbonate is, for example,preferred.

The adhesive fluorine-containing polymer of the present invention can beused as a molding material for producing various molded products. Insuch a case, various fillers such as inorganic powder, glass fiber,carbon fiber, metal oxide or carbon, may be blended within a range notto impair the properties. Further, other than the fillers, a pigment, anultraviolet absorbent or other optional additives may be mixed theretodepending upon the particular purpose. Further, other than suchadditives, a resin such as another fluorine resin or a thermoplasticresin may be incorporated to produce a blend resin. These additives maybe incorporated to the grafting reaction system so that the graftingreaction is conducted in the presence of the additives.

Using the adhesive fluorine-containing polymer of the present inventionas a molding material, a molded product can be produced by aconventional molding method such as injection molding, extrusionmolding, co-extrusion molding, inflation molding, coating or insertmolding employing a mold. Further, a laminate can be produced byco-extrusion molding. Further, a film or sheet may be produced, and sucha film or sheet may be laminated with other molded product to obtain alaminate.

More preferably, the adhesive fluorine-containing polymer of the presentinvention is formed into a molded product by a method wherein thegrafting and molding of the fluorine-containing polymer are carried outalmost simultaneously. As mentioned above, at the time of conductinginjection molding, extrusion molding, co-extrusion molding or inflationmolding, grafting of the fluorine-containing polymer is carried out atthe resin melt-mixing zone of the molding machine, and the molding iscontinuously conducted, to obtain a molded product of the adhesivefluorine-containing polymer. As the molded product, a molded productwhich can be used as a material for producing a laminate, such as a filmor sheet is preferred. Such a film or a sheet may be laminated withanother molded product to obtain a laminate.

The adhesive fluorine-containing polymer of the present invention ismost preferably employed for producing a laminate utilizing its adhesiveproperty. As a method for producing a laminate, it is preferred toemploy a method wherein molding and production of a laminate aresimultaneously conducted by co-extrusion molding. In such a case, it ispreferred to employ a method wherein, as mentioned above, grafting ofthe fluorine-containing polymer and the co-extrusion molding areconducted substantially simultaneously. By conducting the grafting andthe co-extrusion molding simultaneously, it is possible to obtain alaminate such as a laminated film, a laminated sheet, a laminated tubeor a laminated pipe having a layer of the adhesive fluorine-containingpolymer of the present invention, in one step.

The laminate in the present invention is a laminate which has at leastone layer of the adhesive fluorine-containing polymer of the presentinvention, and at least one layer which is in contact with the layer ofthe adhesive fluorine-containing polymer of the present invention, is alayer other than the adhesive fluorine-containing polymer of the presentinvention (hereinafter referred to as a layer of the substrate). Thematerial of the substrate is not particularly limited and may be made ofvarious organic materials or inorganic materials. However, it ispreferably made of various resins. More preferably, it is made of athermoplastic resin to which melt molding such as extrusion molding canbe applied. The material of the substrate may, for example, be afluorine-containing elastomer or a fluorine-containing resin made of afluorine-containing polymer other than the adhesive fluorine-containingpolymer of the present invention. Particularly preferred is amelt-moldable fluorine-containing resin or fluorine-containingelastomer.

The laminate in the present invention is preferably a laminate wherebythe characteristics of the adhesive fluorine-containing polymer of thepresent invention are fully provided. Namely, the adhesivefluorine-containing polymer of the present invention has acharacteristic such that it not only has an adhesive property to afluorine-containing resin or a fluorine-containing elastomer but alsohas an adhesive property to other materials such as other resins.Accordingly, it is possible to obtain, for example, a laminate havingexcellent interlaminar adhesion with a construction of Y/X/Z where X isthe layer of the adhesive fluorine-containing polymer of the presentinvention, Y is the layer of the fluorine-containing elastomer or thefluorine-containing resin made of a fluorine-containing polymer otherthan the adhesive fluorine-containing polymer of the present invention,and Z is a layer made of a resin other than the resins for the layers Xand Y. Further, a laminate with a construction of Y/X can be used as asurface coating material for various substrates or articles by virtue ofthe adhesive property of the layer X. For example, such a surfacecoating material of a film form may be laminated on the surfaces ofsubstrates made of various materials by e.g. heat pressing. Further,when the adhesive fluorine-containing polymer of the present inventionhas the same level of the high physical properties as thefluorine-containing polymer before grafting, a laminate with aconstruction of X/Z is also useful.

As a specific example of the laminate of the present invention, alaminated tube with a construction of ETFE/grafted ETFE/nylon may bementioned (here, ETFE layer is an inner layer). This laminated tube canbe produced in one step by co-extrusion molding. This laminated tube isexcellent in the chemical property such as chemical resistance by virtueof the ETFE inner layer and excellent in the physical property such asthe strength by virtue of the nylon outer layer and the grafted ETFEadhesive layer and has a feature that it is substantially free fromexudation of gasoline. Accordingly, this laminated tube has an excellentproperty as a tube for transporting a liquid fuel for automobiles.

The substrate in contact with the adhesive fluorine-containing polymerlayer of the present invention is not limited to the above resin andmay, for example, be a substrate made of an inorganic material such as ametal sheet, a glass sheet or a ceramic sheet. Otherwise, it may be acomposite substrate such as a resin-coated metal sheet. Further, theadhesive fluorine-containing polymer of the present invention may becoated on a substrate in the form of a solution or a powder.

As mentioned above, it is known to graft an unsaturated compound havinga hydrolyzable group containing a silyl group as a crosslinkable groupto polyvinylidene fluoride, followed by crosslinking with water.However, the crosslinked polyvinylidene fluoride is poor in the adhesiveproperty, and with a polyvinylidene fluoride having a high crosslinkingdegree, melt-molding such as extrusion molding is difficult.Accordingly, in the present invention, when the functional group in thegrafting compound has a crosslinkable property, it is necessary to carryout the molding and the lamination before the adhesive property or themoldability is lost by the progress of crosslinking of the crosslinkablefunctional groups of the grafted fluorine-containing polymer. Likewise,a film or sheet of the grafted fluorine-containing polymer is requiredto be laminated before the adhesive property is lost by the progress ofcrosslinking of the crosslinkable functional groups. After the finaladhesion, molding or lamination has been completed, crosslinking by thecrosslinkable functional groups may proceed.

The laminate in the present invention is preferably a laminate having alayer of a fluorine-containing polymer or the adhesivefluorine-containing polymer on its surface. By the presence of such afluorine-containing polymer surface layer, properties of thefluorine-containing polymer, such as the chemical resistance, solventresistance, oil resistance, gas barrier property, water repellency, oilrepellency, weather resistance, corrosion resistance, water-proofingproperty and anti-soiling property, will be imparted to the surface ofthe substrate.

Now, the present invention will be described in further detail withreference to Examples. However, it should be understood that the presentinvention is by no means restricted to such specific Examples.

EXAMPLE 1

Using a three layer co-extrusion molding machine, a laminated tube witha construction of inner layer/intermediate layer/outer layer was moldedso that the inner diameter was 6 mm, and the thicknesses of innerlayer/intermediate layer/outer layer were 0.4 mm/0.2 mm/0.6 mm,respectively.

To the cylinder for forming the inner layer, atetrafluoroethylene-ethylene copolymertetrafluoroethylene/ethylene/(perfluorobutyl)-ethylene=52/46.5/1.5(molar ratio), hereinafter referred to as copolymer A! was supplied, andto the cylinder for forming the outer layer, nylon 12 (manufactured byUbe Kosan K.K.) was supplied. To the cylinder for forming theintermediate layer, a mixture comprising 100 parts by weight of a powderof the copolymer A, 1.1 parts by weight of maleic anhydride and 0.2 partby weight of dicumyl peroxide, was supplied and reacted at the meltingzone of the cylinder at 330° C. for a residence time of one minute, toform a graft polymer, which was then transferred to the transport zoneof the cylinder. The processing temperatures of the copolymer A, thegraft polymer and the nylon 12 at the transport zone were 260° C., 240°C. and 260° C., respectively, and the temperature of the co-extrusiondie was 260° C.

The peel strength of the obtained laminated tube was measured, wherebymaterial breakage took place as between the layer of the copolymer A andthe layer of the graft polymer, and the peel strength as between thelayer of the graft polymer and the layer of the nylon 12 was 4.3 kg/cm.

EXAMPLE 2

Using a three layer co-extrusion molding machine, a laminated tube witha construction of inner layer/intermediate layer/outer layer was moldedso that the inner diameter was 6 mm, and the thicknesses of innerlayer/intermediate layer/outer layer were 0.4 mm/0.2 mm/0.6 mm,respectively.

To the cylinder for forming the inner layer, the copolymer A wassupplied, and to the cylinder for forming the outer layer, PBT (productNo.: 1401X07, manufactured by Toray Corporation) was supplied. To thecylinder for forming the intermediate layer, a mixture comprising 100parts by weight of a powder of the copolymer A, 1.5 parts by weight ofmaleic anhydride and 0.2 part by weight of t-butyl hydroperoxide, wassupplied and reacted at the melting zone of the cylinder at 330° C. fora residence time of one minute, to form a graft polymer, which was thentransferred to the transport zone of the cylinder. The processingtemperatures of the copolymer A, the graft polymer and the PBT at thetransport zone were 260° C., 255° C. and 260° C., respectively, and thetemperature of the co-extrusion die was 260° C.

The peel strength of the obtained laminated tube was measured, wherebymaterial breakage took place as between the layer of the copolymer A andthe layer of the graft polymer, and the peel strength as between thelayer of the graft polymer and the layer of the PBT was 4.0 kg/cm.

EXAMPLE 3

Using a two layer co-extrusion molding machine, a laminated tube with aconstruction of inner layer/outer layer was molded so that the innerdiameter was 6 mm, and the thicknesses of inner layer/outer layer were0.3 mm/0.6 mm, respectively.

To the cylinder for forming the inner layer, a uniform mixturecomprising 100 parts by weight of a powder of the copolymer A, 1.2 partsby weight of vinyl trimethoxysilane and 1.5 parts by weight of dicumylperoxide, was supplied and reacted at the melting zone of the cylinderat 330° C. for a residence time of one minute, to form a graft polymer,which was then transferred to the transport zone of the cylinder. To thecylinder for forming the outer layer, the same nylon 12 as used inExample 1 was supplied. The processing temperatures of the graft polymerand the nylon 12 at the transport zone were 240° C. and 260° ,respectively, and the temperature of the co-extrusion die was 260° C.

The peel strength of this laminated tube was measured, whereby the peelstrength was 5.5 kg/cm. Further, an immersion text (using fuel C) wasconducted in accordance with JIS K6301 (1975), whereby the peel strengthafter immersion at 40° C. for 70 hours (hereinafter referred to as theimmersion test peel strength) was 4.9 kg/cm.

EXAMPLE 4

Using a two layer co-extrusion molding machine, a laminated tube with aconstruction of inner layer/outer layer was molded, so that the innerdiameter was 6 mm, and the thicknesses of inner layer/outer layer were0.3 mm/0.6 mm, respectively.

To the cylinder for forming the inner layer, a uniform mixturecomprising 100 parts by weight of a powder of polyvinylidene fluoride,1.2 parts by weight of vinyl trimethoxysilane and 1.2 parts by weight ofdicumyl peroxide, was supplied and reacted at the melting zone of thecylinder at 220° C. for a residence time of one minute, to form a graftpolymer, which was then transferred to the transport zone of thecylinder. To the cylinder for forming the outer layer, the same nylon 12as used in Example 1 was supplied. The processing temperatures of thegraft polymer and the nylon 12 at the transport zone were 240° C. and260° , respectively, and the temperature of the co-extrusion die was260° C.

The peel strength of this laminated tube was measured, whereby the peelstrength was 4.9 kg/cm. Further, the immersion text peel strength was4.1 kg/cm.

EXAMPLE 5

Using a two layer co-extrusion molding machine, a laminated tube with aconstruction of inner layer/outer layer was molded, so that the innerdiameter was 6 mm, and the thicknesses of inner layer/outer layer were0.3 mm/0.6 mm, respectively.

Preliminarily, 0.2 part by weight of benzoyl peroxide was added as apolymerization initiator to a mixture comprising 0.9 part by weight oft-butyl peroxymethacryloyloxymethyl carbonate, 23 parts by weight ofstyrene and 10 parts by weight of glycidyl methacrylate, andpolymerization was carried out at a temperature of from 60° to 65° C. toobtain a polymer (hereinafter referred to as peroxy polymer A).

To the cylinder for forming the inner layer, a uniform mixturecomprising 100 parts by weight of a powder of the copolymer A and 33parts by weight of the peroxy polymer A, was supplied and reacted at themelting zone of the cylinder at 300° C. for a residence time of oneminute, to form a graft polymer, which was then transferred to thetransport zone of the cylinder. To the cylinder for forming the outerlayer, the same nylon 12 as used in Example 1 was supplied. Theprocessing temperatures of the graft polymer and the nylon 12 at thetransport zone were 260° C. and 260°, respectively, and the temperatureof the co-extrusion die was 260° C.

The peel strength of this laminated tube was measured, whereby the peelstrength was 3.6 kg/cm. Further, the immersion test peel strength was3.2 kg/cm.

EXAMPLE 6

100 parts by weight of a powder of the copolymer A, 1.5 parts by weightof maleic anhydride and 1.5 parts by weight of dicumyl peroxide werepreliminarily uniformly mixed and melt-mixed by a twin screw extruder at300° C. for a residence time of one minute, to obtain a graft polymerhaving maleic anhydride grafted. This graft polymer was pressed at 300°C. to form a film having a thickness of 0.1 mm. On the other hand, apowder of nylon 12 (product No.: 5016XHP, manufactured by TorayCorporation) was press-molded at 240° C. to obtain a nylon film having athickness of 0.1 mm. This nylon film and the above graft polymer filmwere pressed at a temperature of 220° C to obtain a laminated film. Thepeel strength of this laminated film was 6.2 kg/cm. Further, theimmersion test peel strength was 5.3 kg/cm.

EXAMPLE 7

100 parts by weight of a powder of polyvinyl fluoride, 1.5 parts byweight of maleic anhydride and 1.5 parts by weight of dicumyl peroxidewere preliminarily uniformly mixed and melt-mixed by a twin screwextruder at 200° C. for a residence time of one minute, to obtain agraft polymer having maleic anhydride grafted. This graft polymer waspressed at 200° C. to obtain a film having a thickness of 0.1 mm. Tothis film, a nylon film having a thickness of 0.1 mm (the same as usedin Example 6) was pressed at a temperature of 240° C. to obtain alaminated film. The peel strength of this laminated film was 3.8 kg/cm.Further, the immersion test peel strength was 3.2 kg/cm.

EXAMPLE 8

100 parts by weight of a powder of a tetrafluoroethylene-ethylenecopolymer tetrafluoroethylene/ethylene/propylene =40/30/30 (molarratio)!, 1.5 parts by weight of glycidyl methacrylate and 1.5 parts byweight of dicumyl peroxide were preliminarily uniformly mixed andmelt-mixed by a twin screw extruder at 180° C. for a residence time ofone minute, to obtain a graft polymer having glycidyl methacrylategrafted. This graft polymer was pressed at 120° C. to obtain a filmhaving a thickness of 0.1 mm. This graft polymer film and the same nylonfilm as used in Example 6 were laminated at 120° to obtain adouble-layer laminated film. The peel strength of this laminated filmwas 7.1 kg/cm. Further, the immersion test peel strength was 5.5 kg/cm.

EXAMPLE 9

100 parts by weight of a powder of a tetrafluoroethylene-propylenecopolymer tetrafluoroethylene/propylene=55/45 (molar ratio), hereinafterreferred to as copolymer B!, 1.5 parts by weight of maleic anhydride and0.5 part by weight of dicumyl peroxide were preliminarily uniformlymixed and melt-mixed by a twin screw extruder at 200° C. for a residencetime of two minutes, to obtain a graft polymer having maleic anhydridegrafted. This graft polymer was laminated on the same film as used inExample 6 by calendar rolling to obtain a double layer laminated film.The peel strength of this laminated film was conducted, whereby thetetrafluoroethylene-propylene copolymer underwent cohesive failure.

EXAMPLE 10

100 parts by weight of a powder of polyvinylidene fluoride, 1.5 parts byweight of maleic anhydride and 1.5 parts by weight of dicumyl peroxidewere preliminarily uniformly mixed and melt-mixed by a twin screwextruder at 220° C. for a residence time of one minute, to obtain a filmhaving a thickness of 0.1 mm made of a graft polymer having maleicanhydride grafted. This graft polymer film was laminated with the samenylon 12 film as used in Example 6 at 240° C. to obtain a double layerlaminated film. The peel strength of this laminated film was 6.5 kg/cm.Further, the immersion test peel strength was 6.1 kg/cm.

EXAMPLE 11

100 parts by weight of a vinylidene fluoride/hexafluoropropylenecopolymer vinylidene fluoride/hexafluoropropylene=95/5 (molar ratio)!,1.0 part by weight of maleic anhydride and 1.5 parts by weight ofdicumyl peroxide were preliminarily uniformly mixed and melt-mixed by atwin extruder at 180° C. for a residence time of one minute, to obtain afilm having a thickness of 0.1 mm made of a graft polymer having maleicanhydride grafted. This graft polymer film was laminated with the samenylon 12 film as used in Example 6 to obtain a double layer laminatedfilm. The peel strength of this laminated film was 4.2 kg/cm. Further,the immersion test peel strength was 3.9 kg/cm.

EXAMPLE 12

Using the same composition of starting materials for grafting copolymerA as used in Example 6, a film of a graft polymer having a thickness of0.2 mm was prepared by an extrusion molding machine under the samegrafting and molding conditions as in Example 1. This film of thegrafted copolymer A was melted and laminated on a glass sheet at 330° C.The peel strength of this laminated was 5 kg/cm.

EXAMPLE 13

Using the same composition of starting materials for grafting copolymerA as used in Example 2, a film of a graft polymer having a thickness of1 mm was prepared by an extrusion molding machine under the samegrafting and molding conditions as in Example 2. This film of thegrafted copolymer A was melted and laminated on a stainless steel(SUS-304) sheet. The peel strength of this laminated was 4.8 kg/cm.

Comparative Example 1

A laminate with a construction of copolymer A/nylon 12 was prepared inthe same manner as in Example 6 except that the copolymer A was used byitself in Example 6. The peel strength of this laminate was 0.1 kg/cm.

Comparative Example 2

A laminated film with a construction of polyvinyl fluoride/nylon 12 wasprepared in the same manner as in Example 7 except that polyvinylfluoride was used by itself in Example 7. The peel strength of this filmwas 0.1 kg/cm.

Comparative Example 3

The copolymer B as used in Example 9 was, without grafting, laminatedwith a film of nylon 12 by calender rolling. This laminate was subjectedto a peel test, whereby the two films were found to be not bonded atall.

What is claimed is:
 1. An adhesive fluorine-containing polymercomprising a tetrafluoroethylene-ethylene copolymer as afluorine-containing polymer having hydrogen atoms bonded to carbon atomsof its main chain, and a grafting compound having a linking groupcapable of grafting to the fluorine-containing polymer and a functionalgroup capable of providing an adhesive property, grafted to thefluorine-containing polymer by the use of a radical-forming agent, at aradical-forming temperature, wherein the grafting compound is a compoundhaving a linking group selected from the group consisting of an organicgroup having an α,β-unsaturated double bond at its terminal, a peroxygroup and an amino group, and at least one functional group selectedfrom the group consisting of a carboxyl group, a carboxylic anhydrideresidue, an epoxy group and a hydrolyzable group containing a silylgroup.
 2. The adhesive fluorine-containing polymer according to claim 1,wherein the grafting compound is maleic anhydride.
 3. A method forproducing an adhesive fluorine-containing polymer, which comprisesmelt-mixing a tetrafluoroethylene-ethylene copolymer as afluorine-containing polymer having hydrogen atoms bonded to carbon atomsof its main chain, a grafting compound having a linking group capable ofgrafting to the fluorine-containing polymer and a functional groupcapable of providing an adhesive property, wherein the grafting compoundis a compound having a linking group selected from the group consistingof an organic group having an α,β-unsaturated double bond at itsterminal, a peroxy group and an amino group, and at least one functionalgroup selected from the group consisting of a carboxyl group, acarboxylic anhydride residue, an epoxy group and a hydrolyzable groupcontaining a silyl group, and a radical-forming agent, at aradical-forming temperature, to graft the grafting compound to thefluorine-containing polymer.
 4. The method for producing an adhesivefluorine-containing polymer according to claim 3, the grafting compoundis maleic anhydride.
 5. The adhesive fluorine-containing polymeraccording to claim 1, wherein the radical-forming agent is a peroxycompound.
 6. The adhesive fluorine-containing polymer according to claim5, wherein the peroxy compound is a diacyl peroxide, a ketone peroxide,a hydroperoxide or a peroxy carbonate.
 7. The adhesivefluorine-containing polymer according to claim 1, wherein the graftingcompound consists essentially of said functional group containingcompound capable of providing an adhesive property to the polymer. 8.The method for producing an adhesive fluorine-containing polymeraccording to claim 3, wherein the radical-forming agent is a peroxycompound.
 9. The method for producing an adhesive fluorine-containingpolymer according to claim 8, wherein the peroxy compound is a diacylperoxide, a ketone peroxide, a hydroperoxide or a peroxy carbonate. 10.The method for producing an adhesive fluorine-containing polymeraccording to claim 3, wherein the grafting compound consists essentiallyof said functional group containing compound capable of providing anadhesive property to the polymer.
 11. The adhesive fluorine-containingpolymer according to claim 1, having a peel strength of at least 3.6kg/cm.
 12. The method according to claim 3, wherein the adhesivefluorine-containing polymer has a peel strength of at least 3.6 kg/cm.